STLE: tweaks to createGraph tutorial scripts

tutorials/combustion/chemFoam/gri/validation/createGraph

 #!/bin/sh
 
 gnuplot<<EOF
-    set terminal postscript eps color enhanced
+    set terminal postscript eps color enhanced "Helveicta,20"
     set output "OF_vs_CHEMKINII.eps"
-    set xlabel "Time / [s]"
-    set ylabel "Temperature / [K]"
+    set xlabel "Time / [s]" font "Helveicta,24"
+    set ylabel "Temperature / [K]" font "Helveicta,24"
     set grid
     set key left top
     set xrange [0:0.07]
-    set yrange [1000:2700]
+    set yrange [750:2750]
+    set ytic 250
     plot \
-        "../chemFoam.out" u 1:2 t "OpenFOAM" with points lt 1 pt 6,\
+        "../chemFoam.out" u 1:2 t "OpenFOAM" with points lt 1 pt 6 ps 1.5,\
         "chemkinII" with lines title "Chemkin II" lt -1
 EOF
 

tutorials/combustion/chemFoam/h2/validation/createGraph

 #!/bin/sh
 
 gnuplot<<EOF
-    set terminal postscript eps color enhanced
+    set terminal postscript eps color enhanced "Helvetica,20"
     set output "OF_vs_CHEMKINII.eps"
-    set xlabel "Time / [s]"
-    set ylabel "Temperature / [K]"
+    set xlabel "Time / [s]" font "Helvetica,24"
+    set ylabel "Temperature / [K]" font "Helvetica,24"
     set grid
     set key left top
     set xrange [0:0.001]
-    set yrange [1000:2400]
+    set yrange [750:2750]
+    set ytic 250
     plot \
-        "../chemFoam.out" u 1:2 t "OpenFOAM" with points lt 1 pt 6,\
+        "../chemFoam.out" u 1:2 t "OpenFOAM" with points lt 1 pt 6 ps 1.5,\
         "chemkinII" with lines title "Chemkin II" lt -1
 EOF
 

tutorials/combustion/chemFoam/ic8h18/validation/createGraph

 #!/bin/sh
 
 gnuplot<<EOF
-    set terminal postscript eps color enhanced
+    set terminal postscript eps color enhanced "Helvetica,20"
     set output "OF_vs_CHEMKINII.eps"
-    set xlabel "Time / [s]"
-    set ylabel "Temperature / [K]"
+    set xlabel "Time / [s]" font "Helvetica,24"
+    set ylabel "Temperature / [K]" font "Helvetica,24"
     set grid
     set key left top
     set xrange [0:0.01]
-#    set yrange [800:2800]
+    set yrange [750:2750]
+    set ytic 250
     plot \
-        "../chemFoam.out" u 1:2 t "OpenFOAM" with points lt 1 pt 6,\
+        "../chemFoam.out" u 1:2 t "OpenFOAM" with points lt 1 pt 6 ps 1.5,\
         "chemkinII" with lines title "Chemkin II" lt -1
 EOF
 

tutorials/combustion/chemFoam/nc7h16/validation/createGraph

 #!/bin/sh
 
 gnuplot<<EOF
-    set terminal postscript eps color enhanced
+    set terminal postscript eps color enhanced "Helvetica,20"
     set output "OF_vs_CHEMKINII.eps"
-    set xlabel "Time / [s]"
-    set ylabel "Temperature / [K]"
+    set xlabel "Time / [s]" font "Helvetica,24"
+    set ylabel "Temperature / [K]" font "Helvetica,24"
     set grid
-    set key left top
+    set key left top 
     set xrange [0:0.001]
-    set yrange [800:2800]
+    set yrange [750:2750]
+    set ytics 250 
     plot \
-        "../chemFoam.out" u 1:2 t "OpenFOAM" with points lt 1 pt 6,\
+        "../chemFoam.out" u 1:2 t "OpenFOAM" with points lt 1 pt 6 ps 1.5,\
         "chemkinII" with lines title "Chemkin II" lt -1
 EOF